31.8 Macros with the m4 Technique

The various features of the m4 technique use uppercase single-character macro names. The complete list of them is shown in Table 31.5 . Some of these are defined by using the appropriate define m4 command (see below). Others are predefined for you by the m4 technique. See the appropriate section reference for a full description of how to use each macro.

Table 31.5: Macros Reserved with the m4 Technique

Macro		Description
$B	Section 31.10.5, $B	The BITNET relay
$C	Section 31.10.9, $C	The hostname of the DECnet relay
$E	Section 31.10.13, $E	X.400 relay (unused)
$F	Section 31.10.15, $F	FAX relay
$H	Section 31.10.18, $H	The mail hub
$L	Section 31.10.23, $L	Unknown Local User relay
$M	Section 31.10.25, $M	Who we are masquerading as
$R	Section 31.10.32, $R	The relay for unqualified names (deprecated)
$S	Section 31.10.34, $S	The Smart Host
$U	Section 31.10.37, $U	The UUCP name to override $k
$V	Section 31.10.39, $V	The UUCP relay (for class $=V )
$W	Section 31.10.41, $W	The UUCP relay (for class $=W )
$X	Section 31.10.43, $X	The UUCP relay (for class $=X )
$Y	Section 31.10.45, $Y	The UUCP relay for unclassified hosts
$Z	Section 31.10.47, $Z	The version of this m4 configuration

A few m4 macros can be defined by using the m4 define command. For example, here is how you define the BITNET relay with the BITNET_RELAY keyword:

define(`BITNET_RELAY', `

host.domain

')dnl

See Table 31.6 for a list of those m4 macros that can be defined. The leftmost column in that table shows the keyword to use.

Table 31.6: Macros Declared with Special m4 Names

m4 name	Macro		Description
BITNET_RELAY	$B	Section 31.10.5	The BITNET relay
confCF_VERSION	$Z	Section 31.10.47	The version of this m4 configuration
confDOMAIN_NAME	$j	Section 31.10.20	Official canonical name
confMAILER_NAME	$n	Section 31.10.26	Error message sender
FAX_RELAY	$F	Section 31.10.15	FAX relay
LUSER_RELAY	$L	Section 31.10.23	Local user relay
MAIL_HUB	$H	Section 31.10.18	The mail hub